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14.1 Earth History
Fossils and Geologic Time Scale
| Question | Answer |
|---|---|
| When Earth Formed... billion years ago | 4.6 billion years ago |
| Briefly describe features of the Early Earth | Molten with volcanic features |
| Briefly describe the Early Atmosphere... What was missing? | similar to gases expelled by volcanoes.... Little or no free oxygen |
| When were the earliest fossils ? Earlier evidence of life was found in chemical markings... when were these chemical markings | 3.5 bya 3.8 bya |
| Preserved evidence of organisms | Fossils |
| Discuss the Fossil Record Analogy | It is like a book with many missing pages .. are still filling in the gaps |
| What word can describe the percentage of organisms preserved as fossils ( hint: all, most, tiny amount) | tiny amount |
| What happens to most organisms before they have a chance to become fossilized? | they decay |
| what situation provides the most fossils? | organisms buried rapidly in sediment... most frequently in a watery environment |
| What word describes a fossil that is an impression of the organism | MOLD |
| How is the fossil called a CAST different from the fossil called a MOLD | the cast is filled in with sediment |
| Footprints, burrows and fossilized feces provide indirect evidence of organisms ...they are called | trace fossils |
| How does petrified wood form ? | empty areas were filled in with minerals. ( may happen in a swampy area where trees become submerged) |
| Preserved Tree sap that may trap and entire organism ( many insects are in this substance) | Amber |
| Two things that preserve the original organisms | Mummification and freezing |
| Fossils are more common in ______rock? Why? | Sedimentary ... fossils usually don't survive the heat or pressure needed to form igneous or metamorphic rock |
| The record of Earth's history with major geological and biological events | Geologic Time Scale |
| mya or bya | millions of years ago , billions of years ago |
| Nearly 90% of the earth's entire history ( first 4 billion years) Earth formed, First life, autotrophic prokaryotes enriched atmosphere with oxygen, eukaryotic cells began... and others | Precambrian Time ( supereon) |
| Major changes in Ocean Life, First Life on Land, Swampy Forests( produced much of our coal), Huge insects, tetrapods, first reptiles | Paleozoic era |
| Who were the first land vertebrates... When did they appear | Tetrapods, Paleozoic era |
| What often marks the boundary between the eras etc.. | mass extinctions |
| Era that had dinosaurs as the dominant organisms... also had early mammals, flowering plants and birds | Mesozoic era |
| What is a common hypothesis to explain the extinction of dinosaurs... .When did this occur | meteorite, 65 mya |
| Primary evidence for meteorite impact that caused the dinosaur extinction.. this has high levels of iridium which is rare on earth but common in meteorites.. iridium common on Mars | KT Boundary.. between rocks of mesozoic era and Cenozoic era |
| the most recent era when mammals became dominant land animal | Cenozoic |
| What was true about the first mammals ( hint: size, animal they resemble) | they were small and resembled shrews(mouse) |
Created by:
shemehl
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